Crash test method and apparatus including pitch simulation

Abstract

A crash sled system for simulating the deceleration and pitching motion associated with vehicle crashes. A main sled is accelerated in accordance with vehicle deceleration that occurred during a crash event. A pitching platform is located above and moves with the main sled. Forward and rear guide assemblies are provided which are located along the sides of the pitching platform when the main sled and pitching platform are in the pre-launch position. During launch, the front and rear ends of the pitching platform travel along paths established by the guide assemblies. Prior to launch, the guide assemblies are set to angles of inclination that provide linear approximations to paths for the forward and all ends of the pitching platform that will result in pitching motion experienced by vehicles during the crash events being simulated. Variously configured guide assemblies are disclosed that provide design trade-off between simulation accuracy and system complexity.

1 . A method in which the deceleration and pitching motion associated with vehicle crashes are simulated with a crash sled having a pitching platform located above its upper surface, comprising the steps of:
 determining vehicle crash data representing the relationship between vehicle pitch angle and time;   determining a travel path for the forward end of the pitching platform that is based on the data representing the relationship between vehicle pitch angle and time;   determining a travel path for the aft end of the pitching platform that is based on the data representing the relationship between vehicle pitch angle and time;   applying an acceleration force to the crash sled to accelerate the crash sled and pitching platform in the longitudinal direction;   controlling the forward end of the pitching platform in accordance with the travel path for guiding the forward end of the pitching platform; and   concurrently controlling the aft end of the pitching platform in accordance with the travel path for guiding pitching platform aft end.   
     
     
         2 . The method of  claim 1  wherein:
 the step of determining the travel path for the forward end of the pitching platform and the step of determining the travel path for the aft end of the pitching platform take place prior to the step of accelerating the crash sled and pitching platform; and 
 the steps of controlling the forward and aft ends of the pitching platform are based only on the travel paths for the forward and aft ends of the pitching platform. 
 
     
     
         3 . The method of  claim 2  wherein the travel paths for the forward and rear ends of the pitching platform are substantially straight lines 
     
     
         4 . The method of  claim 1  wherein:
 the step of controlling the forward end of the pitching platform comprises accelerating the front end of the pitching platform along front guide assemblies that are inclined at an angle that aligns the front guide assemblies with a substantially straight line approximation to the travel path for the forward end of the pitching platform; and 
 the step of controlling the aft end of the pitching platform comprises accelerating the aft end of pitching platform along rear guide assemblies that are inclined at an angle that aligns the rear guide assembly with a substantially straight line approximation to the travel path for the aft end of the pitching platform. 
 
     
     
         5 . The method of  claim 4  wherein the front and rear guide assemblies are affixed to a foundation that supports the crash sled during the step of applying an acceleration force. 
     
     
         6 . The method of  claim 4  wherein the steps of accelerating the foreword and aft ends of the pitching platform along the front and rear guide assemblies end upon completion of the pitching simulation. 
     
     
         7 . The method of  claim 6  wherein upward and downward movement of the forward and aft ends of the pitching platform are constrained upon completion of the pitching simulation. 
     
     
         8 . The method of  claim 1  in which the steps of determining the travel paths for the forward and aft ends of the pitching platform comprise determining approximations to the vehicle crash data representing the relationship between vehicle pitch angle and time. 
     
     
         9 . The method of  claim 8  wherein at least one of the approximations to the travel paths for the forward and aft ends of the pitching platform is a substantially straight line approximation. 
     
     
         10 . The method of  claim 8  wherein both of the approximations to the travel paths for the forward and aft ends of the pitching platform are substantially straight line approximations. 
     
     
         11 . The method of  claim 10  wherein:
 the step of controlling the forward end of the pitching platform comprises accelerating the front end of the pitching platform along at least one front guide assembly that is inclined at an angle that aligns the at least one front guide assembly with the substantially straight line approximation to the travel path for the forward end of the pitching platform; and 
 the step of controlling the aft end of the pitching platform comprises accelerating the aft end of pitching platform along at least one rear guide assembly that is inclined at an angle that aligns the at least one rear guide assembly with the substantially straight line approximation to the travel path for the aft end of the pitching platform. 
 
     
     
         12 . The method of  claim 11  wherein the front and rear guide assemblies are affixed to a foundation that supports the crash sled during the step of applying an acceleration force. 
     
     
         13 . The method of  claim 12  wherein the steps of accelerating the foreword and aft ends of the pitching platform along the front and rear guide assemblies end upon completion of the pitching simulation. 
     
     
         14 . The method of  claim 13  wherein upward and downward movement of the forward and aft ends of the pitching platform are constrained upon completion of the pitching simulation. 
     
     
         15 . The method of  claim 1  wherein at least one of the approximations to the travel paths for the forward and aft ends of the pitching platform is a curved line defined by a second degree quadratic expression relating distance traveled to upward and downward movement 
     
     
         16 . The method of  claim 15  wherein both of the approximation to the travel paths for the forward and aft ends of the pitching platform is a curved line defined by a second degree quadratic expression relating distance traveled to upward and downward movement. 
     
     
         17 . The method of  claim 16  wherein:
 the step of controlling the forward end of the pitching platform comprises accelerating the front end of the pitching platform along at least one front guide assembly that is inclined at a predetermined angle that aligns the at least one front guide assembly with a linear approximation to the curved line travel path for the forward end of the pitching platform; and 
 the step of controlling the aft end of the pitching platform comprises accelerating the aft end of the pitching platform along at least one rear guide assembly that is inclined at a predetermined angle that aligns the at least one rear guide assembly with a linear approximation to the curved line travel path for the aft end of the pitching platform. 
 
     
     
         18 . The method of  claim 17  wherein the front and rear guide assemblies are affixed to a foundation that supports the crash sled. 
     
     
         19 . The method of  claim 18  wherein the steps of accelerating the foreword and aft ends of the pitching platform along the front and rear guide assemblies end upon completion of the pitching simulation. 
     
     
         20 . The method of  claim 19  wherein upward and downward movement of the forward and aft ends of the pitching platform are constrained upon completion of the pitching simulation. 
     
     
         21 . An improved method of simulating the pitching motion experienced by one or more vehicles during crash event with a pitching platform that is mounted to and accelerated with a crash sled wherein the improvement comprises:
 determining a substantially straight line approximation to the paths traveled by a forward reference location on the one or vehicles during the crash event;   determining a substantially straight line approximation to the paths traveled during the crash event by a second reference location on the one or more vehicles that is aft of the forward reference location;   controlling movement of the forward end of the pitching platform in accordance with the substantially straight line approximation to the paths traveled by the forward reference location; and   concurrently controlling movement of the aft end of the pitching platform in accordance with the substantially straight line approximation to the paths traveled by the second reference location.   
     
     
         22 . The improved method of  claim 21  wherein
 the step of controlling the forward end of the pitching platform comprises accelerating the front end of the pitching platform along a front guide assembly that defines the substantially straight line approximation to the paths traveled by the forward reference location with the front guide assembly being inclined at an angle that aligns the front guide assembly with the substantially straight line approximation to the path traveled by the forward reference location; and 
 the step of controlling the aft end of the pitching platform comprises accelerating the aft end of pitching platform along a rear guide assembly that defines the substantially straight line approximation to the paths traveled by the second reference location with the rear guide assembly being inclined at an angle that aligns the rear guide assembly with the substantially straight line approximation to the path traveled by the second reference location. 
 
     
     
         23 . The improved method of  claim 22  wherein the front and rear guide assemblies are affixed to a foundation that supports the crash sled and the steps of accelerating the forward and aft ends of pitching platform along the front and rear guide assemblies ends upon completion of the method of simulating the pitching motion. 
     
     
         24 . The improved method of  claim 23  wherein upward and downward movement of the forward and aft ends of the pitching platform are restrained upon completion of the method of simulating the pitching motion. 
     
     
         25 . The improved method of  claim 24  wherein the forward reference location is the vehicle front axle and the second reference location is the vehicle rear axle.